1. Field of the Invention
The present invention relates to a printer apparatus for successively printing respectively different data on printing paper at a high speed and to a printed matter inspecting apparatus for inspecting printed matter on which different data have been successively printed by the printer apparatus.
2. Description of the Related Art
Among the methods for recording desired information on paper or another medium so that it can be visually recognized, there have been known the method of recording the same information on a large amount of media by a printing machine at a high speed, the method of printing respectively different data on a relatively small number of media by a printer used as terminal equipment of a computer, though the printing speed is low, etc.
However, there has also been a strong desire to print a large amount of variable data, that is, data different for every sheet of paper, at a high speed. Therefore, a high speed printer apparatus using for example ink jet heads to print on printing paper which moves at a speed of 5 meters per second, in other words, to print at a speed of at least 15 sheets per second assuming the paper has an A4 size having a side length of about 30 cm or a letter size, is also being commercialized.
Such a printer apparatus is sometimes used for the printing of documents which have to be printed in huge numbers but which also require different numbering or details, for example, stock certificates and other negotiable securities, various types of monetary certificates, or large numbers of bills to be sent to large numbers of customers. When printing such important documents, it is necessary to prevent all mistakes such as duplication or skipping of printed content etc. In addition, even blurring, batter, or other printing defects and variation in line widths or darkness and other low quality printing cannot be allowed. High quality printing of the correct data is required.
In for example a high speed printer apparatus using the ink jet system mentioned above, however, ink spots, blank white areas, and other printing defects called "streakers" are apt to occur. Even in the conventional relatively low speed printer apparatuses of the electrophotographic system, when performing a large amount of printing, unevenness occurs or noise is caused at a considerably high frequency.
In order to prevent such printing defects, it is necessary to keep the printing heads constantly in a good condition. Further, in order to prevent defective printed matter from leaving the premises, it is necessary to inspect the results of the printing by some method or another.
However, it is impossible to visually inspect printed matters printed at a speed of more than 10 sheets per second in real time. Even if the speed is low, a large number of workers and enormous time become necessary for manually inspecting the enormous amount of printed matter. It is also difficult for human workers to visually successively inspect printed matter which is produced. For this reason, there is the disadvantage that it is not possible to fully inspect the printed matter and not possible to completely eliminate the possibility of defective printed matter from being shipped out.